Serum withdrawal-induced post-transcriptional stabilization of cyclooxygenase-2 mRNA in MDA-MB-231 mammary carcinoma cells requires the activity of the p38 stress-activated protein kinase
Bc. Jang et al., Serum withdrawal-induced post-transcriptional stabilization of cyclooxygenase-2 mRNA in MDA-MB-231 mammary carcinoma cells requires the activity of the p38 stress-activated protein kinase, J BIOL CHEM, 275(50), 2000, pp. 39507-39515
Overexpression of the cyclooxygenase-2 (COX-2) gene is observed in several
neoplastic diseases. However, molecular mechanisms involved in the regulati
on of expression of COX-2 are not well understood. In this report, we descr
ibe a unique post-transcriptional regulatory mechanism of COX-2 mRNA stabil
ization in MDA-MB-231 cells, a highly metastatic cell line derived from a h
uman mammary tumor. High levels of COX-2 mRNA, protein, and enzyme activity
were induced by serum withdrawal, which were potently inhibited by the add
ition of serum or >100-kDa serum factor. Nuclear run-on analysis and actino
mycin D chase experiments indicate that regulation is primarily at the leve
l of post-transcriptional mRNA stability. Interestingly, SB203580, an inhib
itor of the p38 stress-activated protein kinase (SAPK), and overexpression
of the dominant-negative p38 alpha construct potently inhibited the serum w
ithdrawal-induced COX-2 mRNA levels. Indeed, the half-life of COX-2 mRNA de
creased from 9 to 4.5 h after SB203580 treatment, suggesting that signal tr
ansduction by the p38 SAPK pathway is required for COX-2 mRNA stability.